Apparatus for sizing a component shell having at least two different cross-sections

ABSTRACT

A method and apparatus forms an exhaust component that includes first and second substrates. An outer shell surrounds the first and second substrates. At least one sensor hole is formed in the outer shell at a location between the first and second substrates. A first end of the outer shell is surrounded with a plurality fingers to size the first end around the first substrate to a first diameter. The plurality of fingers includes an extended finger that is longer than the other fingers such that the extended finger at least partially covers the sensor hole during sizing of the first end. A second end of the outer shell is then surrounded by the fingers to size the second end around the second substrate to a second diameter. The extended finger at least partially covers the sensor hole during sizing of the second end.

TECHNICAL FIELD

The subject invention relates to a method and apparatus for sizing anexhaust component shell having at least two different diameters. Morespecifically, the subject invention relates to sizing a converter shellhaving a sensor hole located between shell portions having differentdiameters.

BACKGROUND OF THE INVENTION

A vehicle exhaust system includes various components that transmitexhaust gases generated by a combustion engine to an ambient outlet. Onesuch exhaust component is a catalytic converter that includes an outershell defining an internal cavity that receives a catalyst substrate.The catalyst substrate can be formed as a single piece or can beseparated into multiple pieces which are referred to as “bricks.”Typically, the substrates are wrapped with an insulating material, e.g.an insulation mat, to reduce heat radiation to adjacent components in avehicle underbody, and to retain or support the substrate in the shell.

During vehicle operation, sensors are often used to monitor certaincatalytic converter characteristics. For example, the catalyticconverter often includes an oxygen sensor. The oxygen sensor is attachedto a sensor boss that is installed on the outer shell. In one knownconfiguration, the sensor boss is attached to an outer shell thatsurrounds a pair of substrates received within the internal cavity.

Typically, the method for manufacturing this type of converterconfiguration includes measuring the substrates, weighing the mats,wrapping the mats around the substrates, and inserting the wrappedsubstrates into a cylindrical outer shell. The shell is then sized, suchas by reducing a diameter of the shell, to a desired diameter based onthe measured substrate and mat weight characteristics. Prior to thestuffing step, a hole is typically punched into the outer shell at alocation between the substrates, and a sensor boss is attached tosurround this hole after the sizing process is completed. Typically, thesensor boss is welded to the outer shell about the hole location.

In certain configurations, the outer shell has to be sized to twodifferent diameters to compensate for component tolerance variation. Forexample, one end of the shell that surrounds one substrate may berequired to be sized to a smaller diameter than an opposite end of theshell that surrounds the other substrate. Traditional sizing operationsfor this type of configuration provide a poor weld area around thesensor hole. The differing diameters can result in large gaps betweenthe boss and the shell at discrete circumferential locations, which isundesirable.

SUMMARY OF THE INVENTION

In one exemplary embodiment, a method for forming an exhaust componentincludes the following steps: providing at least a first substrate and asecond substrate; providing an outer shell that surrounds the first andsecond substrates, the outer shell defining a center axis; forming atleast one sensor hole in the outer shell at a location between the firstand second substrates; surrounding a first end of the outer shell with aplurality fingers to size the first end around the first substrate to afirst diameter, wherein the plurality of fingers includes at least oneextended finger that is longer than the other fingers such that theextended finger at least partially covers the sensor hole during sizingof the first end; and surrounding a second end of the outer shell withthe plurality fingers to size the second end around the second substrateto a second diameter, wherein the extended finger at least partiallycovers the sensor hole during sizing of the second end.

In a further embodiment of the above, the method includes aligning theextended finger to at least partially cover the sensor hole duringsizing of the first end to provide a first surface around one side ofthe sensor hole that is sized to the first diameter.

In a further embodiment of any of the above, one of the first and seconddiameters is greater than the other of the first and second diameters.

In a further embodiment of any of the above, the method includesremoving the first end of the outer shell from the plurality of fingers,rotating the outer shell such that the plurality of fingers surround thesecond end of the outer shell, aligning the extended finger to at leastpartially cover the sensor hole during sizing of the second end toprovide a second surface around an opposite side of the sensor hole thatis sized to the second diameter.

In another example embodiment, the plurality of fingers comprises afirst set of fingers and a second set of fingers, each of the first andsecond sets of fingers including at least one extended finger, and themethod further includes sizing the first end of the outer shell to thefirst diameter with the first set of fingers, and sizing the second endof the outer shell to the second diameter with the second set offingers.

In a further embodiment of any of the above, the method includesattaching a sensor boss to the outer shell at the sensor hole.

In a further embodiment of any of the above, the first substrate has afirst substrate diameter and the second substrate has a second substratediameter greater than the first substrate diameter, and the methodfurther includes wrapping the first substrate with a first mat andwrapping the second substrate with a second mat prior to inserting thefirst and second substrates into the outer shell.

In a further embodiment of any of the above, the method includesmeasuring the first and second substrate diameters prior to wrapping thefirst and second substrates with the first and second mats.

In a further embodiment of any of the above, the method includesweighing the first and second mats prior to wrapping the first andsecond mats around the first and second substrates.

In a further embodiment of any of the above, the method includes sizingthe first end of the outer shell to the first diameter based on ameasured diameter of the first substrate and weight of the first mat,and sizing the second end of the outer shell to the second diameterbased on a measured diameter of the second substrate and weight of thesecond mat.

In another exemplary embodiment, an apparatus is provided for sizing anexhaust component having an outer shell defining a center axis extendingfrom a first shell end to a second shell end, a first substratepositioned within the internal cavity at the first shell end, a secondsubstrate positioned within the internal cavity at the second shell end,and at least one sensor hole formed in the outer shell between the firstand second substrates. The apparatus includes a base coupled to anactuator and a plurality of discrete fingers to surround the first shellend to size the outer shell about the first substrate to a firstdiameter. The fingers surround the second shell end to size the outershell about the second substrate to a second diameter, wherein thefingers extend axially from the base and are circumferentially spacedapart from each other about the central axis. The fingers are defined byan axial length that extends from the base to a distal finger end, andwherein at least one finger has a longer axial length than the otherfingers.

In a further embodiment of any of the above, the at least one fingercomprises only one finger having a longer axial length than the otherfingers.

In another example embodiment, the plurality of fingers comprises afirst set of fingers and a second set of fingers, each of the first andsecond sets of fingers including at least one extended finger, andwherein the first end of the outer shell is sized to the first diameterwith the first set of fingers, and the second end of the outer shell issized to the second diameter with the second set of fingers.

These and other features may be best understood from the followingdrawings and specification.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of a vehicle exhaust system with acatalytic converter incorporating the subject invention.

FIG. 2 is a schematic representation of the catalytic converterincluding two substrates and an outer shell sized to two differentdiameters.

FIG. 3 is a schematic representation of a sensor hole formed in theouter shell at a location between the two substrates.

FIG. 4 is schematic representation of a tool used to size the outershell.

FIG. 5 is a perspective view of the tool showing a plurality of fingersincluding one extended finger.

FIG. 6 is a top view of a distal end of the extended finger in relationto the sensor hole.

DETAILED DESCRIPTION

FIG. 1 shows a vehicle exhaust system 10 that conducts hot exhaust gasesgenerated by an engine 12 through various upstream exhaust components 14to reduce emission and control noise as known. The various upstreamexhaust components 14 can include one or more of the following: pipes,filters, valves, catalytic converters, mufflers etc. In one exampleconfiguration, the upstream exhaust components 14 direct exhaust gasesinto a catalytic converter 16 having an inlet 18 and an outlet 20. Theoutlet 20 communicates exhaust gases to downstream exhaust components22. The various downstream exhaust components 22 can include one or moreof the following: pipes, filters, valves, mufflers etc. These upstream14 and downstream 22 components can be mounted in various differentconfigurations and combinations dependent upon vehicle application andavailable packaging space.

As shown in FIG. 2, the converter 16 has an outer shell 24, alsoreferred to as a can, which defines an internal cavity 26. In theexample shown in FIG. 2, the catalytic converter 16 includes at least afirst substrate 28 and a second substrate 30. The catalyst substrates28, 30 are received within the internal cavity 26. As known, thecatalyst substrate is a substance that speeds up a chemical reactionrate. In an automotive exhaust application, the catalyst substratecomprises an inert substance onto which an active wash coat is added.The catalyst substrate speeds up oxidation of unconverted hydrocarbonsand carbon monoxide into water and carbon dioxide. The materials usedfor the inert substance and active wash coat, and the operation of acatalytic converter is well known and will not be discussed in furtherdetail.

A first mat 32 surrounds the first substrate 28 and a second mat 34surrounds the second substrate 30. The mats 32, 34 are compressedbetween the outer shell 24 and the respective substrates 28, 30 duringsizing of the outer shell 24, which will be discussed in greater detailbelow. The outer shell 24 includes an external surface 36 and aninternal surface 38 that defines the internal cavity 26. The mats 32, 34are compressed directly against the internal surface 38, and provideinsulation and help reduce noise. Any type of insulating mat materialknown in the art could be used for mats 32, 34. The mats 32, 34 arepreferably wrapped around the catalyst substrates 28, 30.

The outer shell 24 defines a central axis A that extends from a firstend 40 to a second end 42. In an area 44 on the outer shell 24 at alocation between the first 28 and second 30 substrates, at least onesensor hole 46 (FIG. 3) is formed. In the example shown, the sensor hole46 has a circular shape. However, any other hole shapes could also beused such as oval, square, rectangular, etc.

A sensor boss 48 is attached to the outer shell 24 and extends outwardlyfrom the external surface 36. Typically, the sensor boss 48 is weldeddirectly to the outer shell 24. The sensor boss 48 can be used for anytype of exhaust sensor; however, the sensor boss 48 is preferably usedfor an oxygen sensor (not shown). The exhaust sensors are used tomeasure and monitor catalytic converter operating characteristics asneeded. The operation of exhaust sensors, such as an oxygen sensor, iswell-known and will not be discussed in further detail.

In one example configuration, the first end 40 of the outer shell issized to a first diameter D1 around the first substrate 28 and thesecond end 42 is sized to a second diameter D2 around the secondsubstrate 30 where the second diameter D2 is greater than the firstdiameter D1. The sensor hole 46 is formed by a punching operation, forexample, prior to the stuffing the first 40 and second 42 ends.Typically, the area 44 in which the hole 46 is formed has a very shortaxial length between the two substrates 28, 30. In such a configuration,this area 44 around the sensor hole 46 will deform to a certain extentduring the sizing operations resulting in different diameters onopposite sides of the hole 46. This makes it difficult to weld thesensor boss 48 to the outer shell 24. Often, a large gap will be formedat one side of the hole 46 which is undesirable. The subject inventionprovides a method and apparatus for sizing the outer shell 24 to providea better welding area around the sensor hole 46.

As discussed above, the outer shell 24 surrounds the first and secondsubstrates 28, 30, which are wrapped in the first 32 and second 34 mats,respectively. The substrates 28, 30 can have variable diameters and themats 32, 34 can have variable weights. In the example shown, the firstsubstrate 28 has a first substrate diameter D3 and the second substratehas a second substrate diameter D4 greater than the first substratediameter D3. The diameters D3 or D4 could be the same with varyingdimensions possibly caused by differences in the mats 32, 34. Further,any difference that does exist between the diameters D3, D4 is verysmall due to component tolerance variation. The difference isexaggerated as schematically shown in FIG. 1 solely for discussionpurposes.

The degree of sizing of the first 40 and second 42 ends is determinedbased on characteristics of the components located within the outershell 24. For example, these characteristics can be related to specificcomponent characteristics of the substrates and/or mats, or of othercomponents located within the outer shell. In one example, the diameterof the substrates and the weight of the mats is used. This example isdescribed in greater detail below.

In one example method of manufacturing the converter 16, the sensor hole46 is formed in the outer shell, the diameters of the substrates 28, 30are measured, and the mats 32, 34 are weighed. After, these steps aretaken, the first mat 32 is wrapped around the first substrate 28 and thesecond mat 34 is wrapped around the second substrate 30. Next, thewrapped substrates 28, 30 are stuffed into the outer shell 24. The shell24 has at least one sensor hole 46 punched into the shell 24 at alocation between the substrates 28, 30 prior to the stuffing step.

A first end 40 of the shell 24 is then sized to the first diameter D1based on the measured diameter of the first substrate 28 and the weightof the first mat 32. The first end 40 refers to the portion of the outershell 24 that surrounds at least the first substrate 28.

As shown in FIGS. 4-6, the sizing process utilizes a sizing tool 50having a base 52 coupled to an actuator 54. A plurality ofcircumferentially spaced fingers 56 extend outwardly from the base 52.At least one of the fingers 56 a is longer than the remaining fingers56. In the preferred configuration, only one extended finger 56 a islonger than the remaining fingers 56. This extended finger 56 a isaligned to extend over and at least partially cover the sensor hole 46during the sizing process for the first end 40. This provides a surfacearound one side of the hole 46 that is sized to the first diameter D1.During the sizing process, the actuator 54 moves the fingers 56 radiallyinwardly toward the center axis A to apply a compressive force F toreduce the outer shell 24 to the specified first diameter D1. Operationof the sizing tool to reduce the outer shell to the desired size is wellknown and will not be discussed in further detail.

Once the first end 40 has been sized to the first diameter D1, the shell24 is removed from the tool 50 and the entire assembly is then flippedaround for the second sizing process. The second end 42 of the shell 24is then surrounded by the fingers 56 and is sized to the second diameterD2 based on the measured diameter of the second substrate 30 and weightof the second mat 34. The second end 42 refers to the portion of theouter shell 24 that surrounds at least the second substrate 30. Theextended finger 56 a is aligned to extend over and at least partiallycover the sensor hole 46 during the second sizing process. This providesa surface around an opposite side of the hole 46 that is sized to thesecond diameter D2, which is greater than the first diameter D1. Duringthe sizing process, the actuator 54 moves the fingers 56 radiallyinwardly toward the center axis A to reduce the outer shell 24 to thespecified second diameter D2.

In another example, the plurality of fingers could comprise a first setof fingers and a second set of fingers, with each of the first andsecond sets of fingers including at least one extended finger 56 a. Assuch, one set of fingers as shown in FIG. 5 would be positioned at oneend of the shell 24 and another set of fingers as shown in FIG. 5 wouldbe positioned at an opposite end of the shell 24. The first end 40 ofthe outer shell is sized to the first diameter D1 with the first set offingers, and the second end 42 of the outer shell is sized to the seconddiameter D2 with the second set of fingers. This embodiment may increasetooling costs as two separate sets of fingers would be required,however, the step of flipping the outer shell around would beeliminated.

In the example shown, as the diameter of the second sizing is greaterthan the first sizing, the extended finger 56 a does not contact theside of the hole 46 that was sized to the first diameter D1 resulting inless deformation. Finally, the sensor boss 48 is then welded to surroundthe sensor hole 46. The area around the hole 46 still has two differentdiameters; however, the surface has a better shape for welding than withtraditional sizing operations.

The fingers 56 extend axially from the base 52 and are circumferentiallyspaced apart from each other about the central axis A. The fingers 56are defined by an axial length L1 that extends from the base 52 to adistal finger end 58. In one example, the axial length L1 extends to alocation that is generally at a center of the hole 46. The extendedfinger 56 a has a longer axial length L2 than the other fingers 56. Inone example, the longer axial length L2 is configured to extend past thehole 46 by a predetermined minimal length such as 5 mm, for example. Thepredetermined minimal length will vary dependent upon the converterconfiguration, size of the substrates, and weight of the mats.

In one example, the distal finger end 58 includes a rounded tip portion60 that extends beyond the distal end 58 to completely cover the hole46. In this example, the fingers 56 are all defined by a common width W1in a circumferential direction. The rounded tip portion 60 does notextend over the entire width W1 of the extended finger 56 a such thatthe extended portion comprising the difference in axial length (L2−L1)comprises a circumferential area surrounding a portion of the hole 56.This provides a process that does not adversely deform the sensor hole46, and which does not result in too much pressure being applied to themats 32, 34. Having only one finger 56 a extend past the hole 46, asopposed to all fingers extending past, creates a better welding areaaround the hole 46 and less deformation, as well as avoiding overcompression of the mat.

Although an embodiment of this invention has been disclosed, a worker ofordinary skill in this art would recognize that certain modificationswould come within the scope of this invention. For that reason, thefollowing claims should be studied to determine the true scope andcontent of this invention.

The invention claimed is:
 1. An apparatus for sizing an exhaustcomponent having an outer shell defining a center axis extending from afirst shell end to a second shell end, a first substrate positionedwithin the internal cavity at the first shell end, a second substratepositioned within the internal cavity at the second shell end, and atleast one sensor hole formed in the outer shell between the first andsecond substrates, the apparatus comprising: a base coupled to anactuator; a plurality of discrete fingers to surround the first shellend to size the outer shell about the first substrate to a firstcross-section and to surround the second shell end to size the outershell about the second substrate to a second cross-section, wherein theplurality of discrete fingers extend axially from the base and arecircumferentially spaced apart from each other about the center axis;wherein each of the plurality of discrete fingers is defined by an axiallength that extends from the base to a distal finger end, wherein theplurality of discrete fingers comprises a first set of fingers and asecond set of fingers, each of the first and second sets of fingersincluding at least one extended finger having a longer axial length thanthe other fingers, and wherein the first end of the outer shell is sizedto the first cross-section with the first set of fingers, and the secondend of the outer shell is sized to the second cross-section with thesecond set of fingers.
 2. The apparatus according to claim 1, whereinwhen the first set of fingers surround the first shell end, the at leastone extended finger of the first set of fingers covers the at least onesensor hole.
 3. The apparatus according to claim 2, wherein when thesecond set of fingers surround the second shell end, the at least oneextended finger of the second set of fingers covers the at least onesensor hole.
 4. The apparatus according to claim 3, wherein theplurality of discrete fingers are moved radially inwardly toward thecenter axis by the actuator to reduce the first shell end to the firstcross-section and to reduce the second shell end to the secondcross-section, wherein one of the first and second cross-sections isgreater than the other of the first and second cross-sections.
 5. Theapparatus according to claim 1, wherein the at least one finger of theplurality of discrete fingers comprises only one finger having thelonger axial length than the other fingers of the plurality of discretefingers.
 6. The apparatus according to claim 1, wherein the distalfinger end includes a rounded tip portion that extends axially beyondthe sensor hole.